U.S. troops tried to burn about 500 copies of the Koran as part of a badly bungled security sweep at an Afghan prison in February, despite repeated warnings from Afghan soldiers that they were making a colossal mistake, according to a U.S. military investigative report released Monday.

The number of copies of the Muslim holy book that were taken to the incinerator at Bagram air base was far greater than U.S. military officials earlier acknowledged in their accounts of an act of desecration that triggered riots across Afghanistan. The incident is also thought to have played at least a partial role in an ensuing increase in attacks against NATO troops by Afghan soldiers and police.

Despite demands from Afghan officials that the American troops be placed on trial over the Koran burnings, U.S. military officials decided against filing criminal charges. Instead, the Army announced that it had taken less-serious disciplinary action against six soldiers for what they described as unintentional — if costly — mistakes.

The investigation, however, cited evidence of a jarring lack of religious awareness and cultural training among the U.S. troops. The report said that before their deployment to Afghanistan, the troops were exposed only to about an hour-long PowerPoint presentation about Islam. Although they were generally aware that the Koran was a holy text, the report said, they were ignorant of the extreme cultural offense their mishandling of it could cause.

The Army did not release the names of the six soldiers because they received only unspecified administrative punishments and did not face criminal charges. A Navy sailor also was investigated, but officials said disciplinary measures were dropped in that case.

Meanwhile, in another case of offensive behavior in the war zone, the Marine Corps said Monday that it disciplined — but stopped short of filing criminal charges against — three noncommissioned officers for their involvement in an incident last year in which Marines videotaped themselves urinating on the corpses of Taliban fighters.

The video became international news after it was posted anonymously to a Web site in January, becoming the latest strain on relations between Afghan civilians and the NATO-led military coalition that has occupied the country for the past decade. The short clip depicts four Marines in combat gear laughing as they relieved themselves over three prostrate bodies.

After a lengthy investigation, the Marine Corps said it determined that the video was recorded in July 2011 by members of the 3rd Battalion, 2nd Marine Regiment while they were deployed to the village of Sandala in Helmand province.

Three Marines pleaded guilty Monday to violations of military regulations but were spared more-serious charges that could have resulted in a court-martial. Because the cases did not go to trial, the Marines Corps declined to identify the three or to disclose the nature of their punishments.

Disciplinary measures are pending against other Marines involved in the case, said Col. Sean D. Gibson, a spokesman for the Quantico-based Marine Corps Combat Development Command. He declined to say how many other Marines might be implicated.

The Army’s investigation of the burning of the Korans documented a series of blunders by U.S. troops and military police officers who — unable to speak local languages — mistakenly assumed that they were disposing of radical literature found in the library of the Parwan detention center, located at the edge of Bagram air base.

Acting on suspicions that prisoners were passing illicit notes in the margins of library books, U.S. troops asked an Afghan translator to take a look. The translator concluded, erroneously, that the majority of the library’s holdings were extremist in nature, according to the investigative report.

Prison guards boxed up almost 2,000 of the suspicious books. Of those, 474 were Korans and 1,100 were unobjectionable religious tracts. The remainder were secular volumes, the investigation found.

When Afghan soldiers and guards at the prison learned of the plan to burn the books, they objected loudly. But U.S. troops, responding to miscommunicated orders as well as suspicions about their Afghan allies, transported the materials to a burn pit at Bagram air base.

Most of the texts were rescued at the last minute by Afghan workers at the base, who quickly shut off the incinerator and doused the flames after realizing that the daily trash pile contained Muslim holy books. The military said, however, that “up to 100” Korans and other religious texts were burned.

Afterward, the Afghans so distrusted Americans to properly handle the saved Korans that they hid them under rugs, in closets and even in kitchen microwaves.

The investigating officer, Army Brig. Gen. Bryan G. Watson, said in the report that he found no evidence of “malicious intent to disrespect the Koran or defame the faith of Islam” on the part of the U.S. troops.

“Ultimately, this tragic incident resulted from a lack of cross-talk between leaders and commands, a lack of senior leader involvement [and] distrust among our US Service Members and our partners,” he concluded.